Abstract

Biological diversity is the key to maintaining life. Therefore preservation of biodiversity is important for sustaining a healthy Earth, but it also is immensely valuable tothe health and lifestyle of human society. Today new methods of auxiliary reproductivetechnology allow using them not only for preservation of reproductive potential of theperson, and also for preservation a biodiversity of wild and endangered species of farmanimals. Captive breeding programs, genetic resource banks and artificial reproductivetechniques have been suggested as important tools for conservation. Today, biotechnological methods, such as artificial insemination and transplantation of embryos are welldeveloped and are used in programs of animal husbandry and preservation. Receivingoocytes and embryos requires stimulation of ovaries on what some time depending ona species of animals usually is required. These methods are not acceptable in case ofemergency, and the in vivo received oocytes in smaller quantity do not guarantee themaximum storage of genetic material. Therefore an alternative method of preservation ofgenetic material is the cryopreservation of immature oocytes in the primordial follicleswhich are located in ovary cortex. The procedure of ovarian tissue cryopreservation permits conservation of hundreds of immature oocytes kept within the protective environment of the original ovarian tissue. An important advantage of this technique that thehormonal stimulation is not required in this case. Additionally, because the primordialfollicles are small and have a simple structure, they are much more tolerant to manipulation and to the freeze-thaw procedure compared with the large growing follicles. A keyelement of a good cryopreservation to cell survival is the physiochemical relationshipof heat and water transport between the intra- and extracellular environment. The art ofcryobiology involves the addition of one or more cryoprotectants which generally reduceboth the eutectic and freezing points. Therefore the purpose of this work is identificationof an optimum method of a cryopreservation of sheep‘s ovarian tissue using of variouscryoprotectors. In the present study, the cryopreservation of indigenous Chui population sheep’s ovarian tissue was conducted in vapors of liquid nitrogen at distance of 5cm from surface within 20 minutes with use of various cryoprotectors: 1,5 M dimethylsulfoxide (DMSO), 1,5 M propylene glycol (PG), 1,5 M ethylene glycol (EG) and 1,5 Mglycerol (HL). The analysis of comparative histology studying shows that use 1,5 M PGand 1,5 M DMSO has more effective effect on viability of ovarian follicles, than use 1,5M EG and 1,5 M HL.Key words: dimethyl sulfoxide, ethylene glycol, freezing, follicles, glycerol, ovariantissue, propylene glycol.